Subterranean well tools are introduced or carried into a subterranean oil or gas well on a conduit, such as wire line, electric line, continuous coiled tubing, threaded work string, or the like, for engagement at a pre-selected position within the well along another conduit having an inner smooth wall, such as casing. These tools include devices such as expandable elastomeric, permanent or retrievable plugs, packers, ball-type and other valves, injectors, perforating guns, tubing and casing hangers, cement plug dropping heads, and other devices typically encountered during the drilling, completion, or remediation of a subterranean well, Such devices and tools will hereafter collectively be referred to as “auxiliary tools.” The auxiliary tool is typically set and anchored into position within the casing such that movements in various directions such as upwardly, downwardly, or rotationally, are resisted, and, in fact, prevented. Such movements may occur as a result of a number of causes, such as pressure differentials across the tool, temperature variances, tubing or other conduit manipulation subsequent to setting for activation of other tools in the well, and the like.
When positioned at the required depth, the auxiliary tool must be set. This typically requires shearing locating pins, setting a “slip” mechanism that engages and locks the auxiliary tool with the casing, and energizing the packing element in the case of setting a plug. This requires large forces, often in excess of 20,000 lbs. The activation or manipulation of some of such auxiliary tools often is achieved by use of some sort of apparatus, commonly referred to as a “setting tool,” which may be introduced into the well along with or subsequent to the auxiliary tool on wire or electric line, continuous or coiled tubing, or by other known means. Many types of setting tools exist. Some of these setting tools are known to apply hydrostatic well pressure within well fluids at the setting or activating depth through the setting apparatus and upon a face of a piston head or the like to move a stroking rod, cylinder or housing member in a direction to activate manipulation of the setting tool. Likewise, some of these setting tools are hydraulically operated, either by use of a pump in the setting tool that develops hydraulic pressure or surface pumps that transmit hydraulic pressure through tubing to the setting tool.
However, the most commonly used setting tools are those that are activated by means of an explosive called a pyrotechnic or “black power” charge to cause an explosion within a portion of the housing of the manipulation tool and the energy defined by this explosion drives such piston, stroking rod, or other member to cause the manipulation of the auxiliary tool. By “explosion” it is meant the continuous generation, sometimes relatively slowly, of energy by electric activation of a power charge-initiated reaction which results in a build up within a chamber of transmittable gaseous pressure within the apparatus. The industry standard explosive setting tool is the Model E-4 Wireline Pressure Setting Assembly, Product No. 437-02, of Baker International Corporation; however others, such as the Halliburton “Shorty” also exist.
After the auxiliary tool is set, the explosive setting tool remains pressurized and must be raised to the surface and depressurized. This typically entails bleeding pressure off the setting tool by rupturing a piercing disk with a piercing screw, thus creating a vent hole that allows the gas within the setting tool to bleed off. Not only is the depressurization of the setting tool dangerous, but it also exposes personal to potentially hazardous chemicals that result from the combustion of the pyrotechnic. Thus, this operation must be carried out under strictly controlled conditions.
While many procedures have been developed to minimize the risks associated with an explosive setting tool, many disadvantages inherent in the use of an explosive setting tool still remain. Explosives are dangerous to handle and difficult to store and maintain on the job site. This requires the use of trained explosives personnel at every stage of operation. Special permits and licenses are often required to comply with State and local safety regulations. Additionally, the use of explosives requires the controlled, gradual lowering of the setting tool. Certain of the prior setting tools have included an orifice in the body of the tool through which oil is forced as detonation occurs to thereby slow the setting action on the device being set. Also, explosives which are “slow burning” are employed in order to lessen the undesirable effects of a sudden explosion. Moreover, the use of explosives requires that the firing chamber of the tool be cleaned after every use, thereby adding to the maintenance requirements of the tool.
Obviously, as can be seen from the above, the use of explosives should be avoided if at all possible. While there are other alternatives available, a large number of explosive setting tools are in use. Therefore there exists a need for a means to convert an explosive setting tool, such as those described above, to non-explosive setting tools.